The objective of this study was to evaluate effect of different thawing procedure to Hypo-Osmotic Swelling Test (HOST), motility and morphology of bull semen. Straw (0.25 ml) frozen semen from 4 Holstein bulls was used in this study. Post-thaw motility, morphology and hypo-osmotic swelling test (HOST) were carried out at 37degreesC for 30 sec, 50degreesC for 15 sec and 70degreesC for 5 sec. According to these protocols motility, defected acrosome, other morphological defects, total morphological defects, and swollen tail spermatozoa (HOST) values were 56.6 %, 56.7 %, 59.8 %; 3.7 %, 2.6 1.9 %; 10.7 %, 8.8 %, 5.6 %; 14.4 %, 11.5 %, 7.5 %; 37.1 %, 37.4 39.3 % respectively. Thawing protocol has affected all sperm characteristics (P < 0.05) except HOST. There was a high correlation between HOST values and motility (P < 0.01) but no correlation was observed between HOST and acrosome defects, other morphological defects and total morphological defects.